The blue-chip FTSE 100 <.FTSE> index fell 0.6 percent - similar to the move on Europe's STOXX benchmark - while mid-cap UK shares <.FTMC> lost 0.8 percent.

The main source of pressure was a slide in crude and base metals prices, with the former down for the fourth day in a row after the International Energy Agency cut its outlook for 2018 oil demand growth [O/R].

Metals prices meanwhile have taken a hit from signs China's economy - the world's top commodities consumer - is slowing.

The FTSE 350 Mining index <.FTNMX1770> fell one percent to the lowest level in more than a month.

"With the miners falling ... it's a very heavily-weighted sector on the FTSE," said Henry Croft, a research analyst at Accendo Markets. "We've been really in a consistent downtrend since the beginning of November."

Shares in mining companies Glencore (>> Glencore), Anglo American (>> Anglo American) and Rio Tinto (>> Rio Tinto) fell around 1.5 percent, recovering slightly from earlier deeper losses [MET/L].

Among oil firms, shares in Royal Dutch Shell fell 1.3 percent and BP (>> BP) declined 1.5 percent.

However, precious metals miners benefited from gold's safe-haven status. Fresnillo (>> Fresnillo) led gains, rising 3.3 percent, and Randgold (>> Randgold Resources) advanced almost one percent.

Fresnillo shares also received a lift from HSBC raising its rating on the stock to "buy" from "hold".

Some telecoms performed strongly too, with BT (>> BT Group) gaining 1.4 percent and Vodafone (>> Vodafone Group) building on the previous session's gains after it lifted its full-year earnings forecast for the first time in recent history.

Vodafone shares added 0.6 percent to near four-month highs - adding to Tuesday's 5 percent jump - as the stock received more price-target upgrades from brokers.

Outside the blue chips, company updates were very much in focus, with some large declines among British mid-caps <.FTMC>.

Talktalk (>> TalkTalk Telecom Group) plummeted as much as 10 percent after a profit warning but closed some 6 percent down on the day, having hit its weakest level since May.

Crest Nicholson (>> Crest Nicholson Holdings PLC) dropped 4.4 percent after flagging weakness in central London property prices. Average house-price growth across the property company's UK business fell to a quarter of that in 2016, it said.

Smaller more UK-focused companies are seen bearing the brunt of the economy's Brexit-related weakness and rising inflation. Latest data showed the number of people in work in Britain fell by the most in more than two years in the three months to September.

Guy Stephens, technical investment director at Rowan Dartington said political uncertainty would also weigh on markets.

"Whilst this persists, and it is likely to get worse before it improves, the UK equity market is off-limits to many international investors," Stephens told clients in a note.

(Reporting by Kit Rees and Sujata Rao; Editing by Richard Balmforth)

By Kit Rees